Asters are popular garden flowers that bloom in late summer and fall. These perennials produce masses of colorful daisy-like flowers on bushy plants. Once the flowers fade, they develop into seed heads containing hundreds of tiny seeds. But what exactly do aster seeds look like?
Aster Seed Anatomy
Aster seeds are very small, measuring just 1-2 millimeters long. They have an oval or somewhat triangular shape
The seed coat is hard and varies in color from dark brown to black This dark outer shell protects the embryo and nutrients inside the seed,
Under this outer covering is the endosperm, which provides food to help the embryo germinate and develop.
At the base of the seed is the minute aster plant embryo This contains everything needed to grow into a new plant
Identifying Traits
- Size: 1-2 mm long
- Shape: Oval or triangular
- Color: Dark brown to black outer seed coat
- Texture: Hard, glossy surface
While tiny, aster seeds have some distinguishable traits that aid identification:
Size: Aster seeds are quite small, measuring just 1-2 mm in length. This is similar in size to a grain of sand.
Shape: Their shape is oval to somewhat triangular. The tapered base of the seed attaches it inside the flower head.
Color: The hard outer seed coat makes aster seeds appear dark brown to black. This protective covering obscures the paler inner seed contents.
Texture: Aster seeds have a smooth, shiny, and glossy texture. Their hard outer surface gives them a polished appearance under magnification.
What Do They Look Like in the Flower Head?
Aster seeds start out nestled in a dense cluster on receptacles inside the flower head. As the petals fade, the base of the flower head dries into a burr-like seed pod.
At first, the developing seeds are yellowish-green, soft, and plump with stored food inside. As they mature, the seeds shrink and turn brownish-black.
The flower head changes from golden yellow to light brown. Fibrous white hairs emerge, giving it a fluffy, cotton-like appearance.
Eventually the seed head opens, dispersing the multitude of tiny seeds to the wind. Some remain trapped within the fuzzy hairs.
Appearance When Harvested
After collecting dried aster flower heads, the seeds must be extracted before storage.
Extraction methods like rubbing the pods between your fingers loosen the seeds, causing them to fall out when the head is shaken.
The harvested seeds will consist of mostly small, dark oval or triangular seeds. Bits of the light papery flower parts will be mixed in too.
To clean, gently blow on the seeds to remove the chaff. Pick out any remaining flower debris to leave just the ripe seeds.
Stages of Development
Aster seeds go through distinct phases of development:
Flowering: Pollination within the flower head fertilizes the ovules, initiating seed growth.
Maturing: As the petals fade, the seeds enlarge within the receptacle, filling with nutrients. Their color changes from green to brownish-black.
Drying: The ripening flower head closes up as the seeds fully mature. The protective seed coat hardens to preserve the embryo.
Dispersal: The dried flower head opens, releasing the mature seeds. Wind and precipitation aid distribution.
Germination: When conditions like moisture, warmth, and light are right, the embryo resumes growth, developing into a seedling.
Viability Over Time
Fresh aster seeds have the highest rates of successful germination. Viability begins to decline as seeds age.
Stored properly in a cool, dry location, aster seeds remain viable for 1 to 3 years. After that germination decreases as food reserves within the seeds deplete.
Extending seed life is possible by refrigerating them in airtight containers. Under ideal storage, aster seeds may last for 4 to 5 years.
Look-Alike Species
Aster seeds can resemble those of related species in the Asteraceae family. These include:
- Daisies
- Sunflowers
- Dahlias
- Zinnias
- Marigolds
While similar, aster seeds tend to be smaller and darker than these. Examining the subtle variations in size, shape, and color helps identify them correctly.
Why Seed ID Matters
Paying attention to aster seed traits is important both for collecting your own seeds and when purchasing them.
When saving seeds from your garden, you want to be sure you’ve harvested aster seeds, not imposters. Proper identification ensures you’ll get the flower you expect when you sow them.
Understanding seed characteristics also helps when buying aster seeds. Reputable suppliers will show images of the actual seeds for sale. Comparing these to your collection ensures you’re getting the real thing.
How To Harvest Aster Seeds // Garden VLOG
FAQ
Are aster seeds hard to germinate?
Do asters drop seeds?
Will asters reseed themselves?
What do aster seeds look like?
Aster seeds range from light to dark brown, and are long with a pointed end. They’re fairly large and easy to handle. Asters aren’t too picky about their first home, but make sure the container you choose has good drainage to prevent waterlogging, which can cause the seeds to rot.
How long do aster seeds take to grow?
Place a humidity dome over the tray until the seeds have sprouted, which should take 10-14 days. Aster seeds need light to germinate, so keep them under grow lights or in a sunny window. Once your aster seedlings have sprouted and are starting to grow, it’s time to think about transplanting them outdoors.
How do you grow asters from seed?
Asters grow best started from seeds sown early indoors: Start seeds indoors 6-8 weeks before your last expected spring frost date. Use a seed starting mix and provide 65°F – 70°F soil temperatures for germination. After sprouting, grow seedlings on at 60°F – 65°F with plenty of light.
Do aster seeds need light?
Aster seeds require light to germinate, so be careful not to cover them with more than ⅛ inches of soil when planting. Learn more about germination light requirements here. When sowing outdoors, spread the seeds across the surface of moistened soil. Do aster seeds need cold stratification?